Port cannot install gnuplot

[matthew20103@…]

When I was trying to install the gnuplot via macports, i.e.

sudo port clean gnuplot sudo port install gnuplot

I got the following messages:

Error: org.macports.build for port gnuplot returned: command execution failed Please see the log file for port gnuplot for details:

/opt/local/var/macports/logs/_opt_local_var_macports_sources_rsync.macports.org_release_tarballs_ports_math_gnuplot/gnuplot/main.log

To report a bug, follow the instructions in the guide:

​http://guide.macports.org/#project.tickets

Error: Processing of port gnuplot failed

After inspecting the main.log file, I found the following error message:

:info:build dyld: Library not loaded: /opt/local/lib/libpng15.15.dylib :info:build Referenced from: /opt/local/lib/libpangocairo-1.0.0.dylib :info:build Reason: Incompatible library version: libpangocairo-1.0.0.dylib requires version 31.0.0 or later, but libpng15.15.dylib provides version 30.0.0

How can I solve this problem?

[matthew20103@…]

Here attached the main.log file, please have a look.